import java.util.HashMap;
import java.util.Map;

public class Cache<K, V> {
    private final Map<K, V> cache;

    public Cache() {
        this.cache = new HashMap<>();
    }

    public void put(K key, V value) {
        cache.put(key, value);
    }

    public V get(K key) {
        return cache.get(key);
    }

    public boolean containsKey(K key) {
        return cache.containsKey(key);
    }

    public void remove(K key) {
        cache.remove(key);
    }

    public void clear() {
        cache.clear();
    }

    public int size() {
        return cache.size();
    }

    public static void main(String[] args) {
        Cache<String, Integer> studentCache = new Cache<>();

        studentCache.put("张三", 18);
        studentCache.put("李四", 20);

        System.out.println("张三的年龄：" + studentCache.get("张三"));
        System.out.println("缓存是否包含王五：" + studentCache.containsKey("王五"));

        studentCache.remove("李四");
        System.out.println("移除李四后缓存大小：" + studentCache.size());

        studentCache.clear();
        System.out.println("清空后缓存大小：" + studentCache.size());
    }
}